Process for the treatment of magnesium-silicon aluminum alloys



3 337 377 PROCESS FOR THF: TliEATMENT F MAG- NESIUM-SILICON ALUMINUM ALLOYS Jacques Bonmarin, La Matte-Servolex, France, assignor United States Patent 0 3,337,377 Patented Aug. 22, '1967 improving aluminum alloys containing magnesium and silicon, which makes it possible to reduce to a considerable extent the effect of the waiting between the quenching and annealing operations. In the case of an air quenching t0 Pechiney, Compagnie de Produits Chimiques et Elecimmediately following a cold-working operation, the inf q f Paris, France stant invention has the eifect of avoiding any reduction 3 f Flled D 1963, 331,381 in the mechanical properties without it being necessary ahhs lmomy! g g 20! 1962 either to modify the thermal treatment or to provide a previous homogenization treatment. 4 Claims (CL 148-159) Another object of the invention is the provision of an The present invention has for its object a process which alloy obtained by using the above process. makes it possible to improve the characteristics of alumi- These and other objects of this invention will appear num alloys containing magnesium and silicon. The invenhereinafter and it will be understood that the specific emtion also relates to the alloys obtained by carrying this bodiments hereinafter set forth are provided solely for process into effect. purposes of illustration and not by way of limitation.

It is well known that the aluminum alloys which con- In the process according to the invention, a quantity of tain magnesium and silicon are capable of being given tin between 0.001 and 0.1 percent and. preferably between improved mechanical properties by quenching from atem- 0.005 and 0.1 percent is added to the aluminum alloy perature at which the metal is entirely or almost entirely containing magnesium and silicon. Typical alloys accordin the state of solid solution. This rapid cooling is then ing to the invention have the following compositions: followed by a natural or artifical aging. Such alloys are magnesium 0 2 to 2% employed either in the cast state or in the transformed si1ic0n 0 2 to'5% state obtained by operations resulting from hot working to 0.1%: or h Such. as forgmg forming rohihg impurities-iron up to 0.5%, others up to 0.2% each, trudlng drawlng and wire-drawing.

. with the total being less than 1%.

The mechamcal characteristlcs obtained after quenchaluminum balance ing and artifical aging, or tempering, are proportionally higher for a quenching of given intensity when the time pfeferredhhow whlch are modlfieh 1h accordahfie Wlth elapsed between these two operations is shorter. It is the 1115mm lhventlon have the f llowing compositions;

only in the case where a cold-hardening operation is imi -414 t 10%,

mediately followed by an air quenching that this disad- 1 0 4 to 1 3% vantage is no longer observed, but then only reduced i 005 t 0,1%

mechanical characteristics are Obtainedimpuritiesiron upto 0.5%, others up to 0.2% each with These facts constitute serious disadvantages for industh t t l being le th 1%, trial production because it is frequently diflicult to orl i nb la e, ganize the production operations in such a wa that the annealing immediately follows the quenching. It is even The alioys referred to hi the following. ehamp 165 were desirable in certain cases to take advantage of the plasigggig by comhosltlons falling wlthm the above ticity imparted to the alloy by the quenching in order to shape it before causing it to be hardened by the annealing. 40 Order. to be best i understand the Subject of In the second case, the necessity of quenching in air immventlon there Is consldehed the ca.se of an alloy mediately after the cold-hardening operation is more Whlch has undergohe an extruhmg i p An aluml' .readily accepted, but the reduction of the mechanical Hum alloy cohtalhmg magnesium and elitiuded characteristics still represents a serious disadvantage. and hh h 1h am on leaving the h Is not Sensmv? to .Inorderto overcome these disadvantages, special and the Walhhg f y h the qhehchlhg f the ahheahhg' frequently troublesome thermal treatments have been proon the h 'y, 11 has not been su.b ected to pr ev1ous PQSML one of these consists in dif i the annealing homogenization, 1t only has medlocre characteristics. conditions, but it necessitates special installations, while Ah addlhoh of tlh then has the effect of ihcrhasihg the another consists in causing bill to b subjected to a mechanical characteristics thereof and makes it possible previous homogenization treatment at a temperature in to obtain, without previous homogenization, characteristhe region of 600 C. before any deformation. tics which are at least equal to those which are provided The present invention has for its object a process for by the alloys homogenized before extrusion.

TABLE NO. 1 NONHOMOGENIZED BILLETS Aging AlloyA Alloy A+0.01% Sn E R A E R A $fter aging fog 115 daytsi .6 6. 3 10. 7 15 8. 3 13. 9 15 i cig fter$1eiiching 15 1s 11 18.6 21.7 19 1 month after quenching 13. 9 17. 8 14 18.8 24. 8 14 HOMO GENIZED BILLE'IS iter aging for daysin 7. 7 12. 5 13 8. 7 15. 2 19 i tiii ne r ri iahiii nl 21.6 24.2 13 20.8 24.3 12 lmonth after quenching 21.8 24.8 14 21.1 25.2 16

E-The elastic limit in kgJmIn. (0.2 percent ofiset). R-Ultimate strength in kgJmm. APercent elongation at rupture.

It is shown from this table that:

(a) The alloy is insensitive to the waiting time between quenching and the annealing;

(b) The addition of a quantity of tin as small as 0.01% causes a considerable improvement in the mechanical characteristics of the non-homogenized alloy.

An alloy of the type referred to, when extruded and quenched in water or oil just after leaving the press is very sensitive to the waiting time between the quenching and the annealing. The addition of tin overcomes this disadvantage.

As a particular example, tin is added in amounts of 0.01 percent and 0.1 percent to an alloy, the composition of which is as follows:

percent Magnesium 0.81 Silicon 0.60 Iron 0.34

The alloy to which no tin is added and the two alloys containing the addition are cast into billets, then extruded under the same conditions Without previous homogenization of the billets. The bars which are obtained are heated for two hours to 560 C., and then quenched in water. They are then subjected to an annealing operation which lasts hours at a temperature of 175 C. The annealing is conducted either immediately after the quenching or after an increasingly long period of time.

The results of the traction test are given by Table No. 2 in which the notations are those which have been set out in respect of Table No. 1.

TABLE NO. 2

Alloy B AlloyB+0.01%Sn Alloy B+O.1% Sn Time* E RA It is shown from this table that:

(a) For the alloy B without additive, the mechanical characteristics are greatly reduced when the waiting time between the quenching and the annealing is increased.

' The effect is very marked, even for short waiting times,

of the order of a few hours.

(b) The addition of the optimum amounts of tin specified to the alloys in question provides highly significant improvements even where the waiting time bet-ween quenching and annealing is of the order of days. These improvements are most apparent when considering the mechanical properties set forth in the above table.

tion are suitable for use in combination with a wide variety of aluminum-magnesium-silicon alloys. The fol- 4 lowing comprises a list of additional elements which may be included in such alloys and which will not affect the improvements provided by the tin additions:

Percent by weight, up to Manganese 6 Chromium 6 Titanium 1 Zirconium 1 Vanadium 1 Boron 0.1

It will also be understood that other additions can be tolerated in alloys of the type described. Thus, alloying elements which are employed in conventional practice for modifying transformation temperatures or for otherwise affecting the mechanical properties of the alloys can be utilized. It will be apparent, however, that such additions are contemplated only where they do not interfere with the function of the tin additions described herein.

It will be understood that various changes and modifications can be made in the processes and alloys described which provide the characteristics of this invention without departing from the spirit thereof particularly as defined in the following claims.

What is claimed is:

1. In a process for the treatment of aluminum base alloys including the steps of subjecting the alloys to a solution heat treatment, and thereafter aging the alloys, said alloys consisting essentially of from 0.2 to 2.0 percent by weight magnesium and from 0.2 to 5.0 percent by weight silicon, and the balance aluminum, said alloys being subject to losses in mechanical properties due to delays between said solution heat treatment and aging, the improvement in combination therewith including tin in said alloys in an amount between 0.001 and -0.1 percent by weight.

2. A process in accordance with claim 1 wherein magnesium is present in said alloys in amounts between 0.4 and 1.0 percent by weight, silicon is present in said alloys in amounts between 0.4 and 0.8 percent by weight, aid iron is present in said alloys in amounts up to 0.5 percent by weight.

3. A process in accordance with claim 1 wherein said alloys contain up to 6 percent by weight manganese, up to 6 percent by weight chromium, up to 1 percent by weight titanium, up to 1 percent by weight zirconium, up to 1 percent by weight vanadium and up to 0.1 percent by weight boron.

4. A process in accordance with claim 1 wherein said tin is included in an amount between 0.005 and 0.1 percent by weight.

References Cited 

1. IN A PROCESS FOR THE TREATMENT OF ALUMINUM BASE ALLOYS INCLUDING THE STEPS OF SUBJECTING THE ALLOYS TO A SOLUTION HEAT TREATMENT, AND THEREAFTER AGING THE ALLOYS, SAID ALLOYS CONSISTING ESSENTIALLY OF FROM 0.2 TO 2.0 PERCENT BY WEIGHT MAGNESIUM AND FROM 0.2 TO 5.0 PERCENT BY WEIGHT SILICON, AND THE BALANCE ALUMINUM, SAID ALLOYS BEING SUBJECTED TO LOSSES IN MECHANICAL PROPERTIES DUE TO DELAYS BETWEEN SAID SOLUTION HEAT TREATMENT AND AGING, THE IMPROVEMENT IN COMBINATION THEREWITH INCLUDING TIN IN SAID ALLOYS IN AN AMOUNT BETWEEN 0.001 AND 0.1 PERCENT BY WEIGHT. 